"T echnically speaking, no one is cut out for monogamy, but at the same time, nearly everyone with a functioning frontal lobe is capable of it."
In The Myth of Monogamy , husband and wife co-authors David P. Barash and Judith Eve Lipton - married for 32 years now - wrote about the rarity of fidelity in the animal world.
Their new book, Strange Bedfellows , examines what humans could learn about their own inclinations from the handful of monogamous animals.
Aside from beavers, serial monogamists who enjoy approximately two relationships per lifetime, it is an obscure list. Among them is the Malagasy giant jumping rat, the California mouse, the fat-tailed dwarf lemur, the pygmy marmoset, the black caped chickadee and the Peruvian warbling ant-bird.
Prof. Barash, an evolutionary biologist, and Dr. Lipton, a psychiatrist, argue that animals and humans become monogamous for the same reason they cheat. Whether it's real estate or task sharing, it all boils down to children, more specifically the propagation of your own genes.
The authors spoke about cheating, fidelity and love with The Globe and Mail from their horse farm near Redmond, Wash.
Are any animals but the flatworm - where the male and female "fuse together at adolescence, remaining sexually faithful ever after" - truly monogamous?
Prof. Barash: No. When we look hard enough at any living species, we find exceptions even in those that we used to think were fully, completely and reliably monogamous.
Dr. Lipton: The test for that is DNA fingerprinting. They're fingerprinting the babies.
Prof. Barash: When you get the DNA results, you find that a certain percentage of offspring are not fathered by the purported father.
Why do people get upset when they find out their favourite monogamous animals aren't monogamous after all? I'm thinking of swans or the embattled masses in March of the Penguins , who actually take up with a new mate every season. Are people afraid it might say something about their own prospects?
Prof. Barash: It's a letdown for a lot of people. People look for validation of their own inclinations and desires in the natural world.
Dr. Lipton: We're looking for stories like Cinderella, where people and animals live happily ever after. The penguins may in fact live happily ever after, year after year with their new partners.
Prof. Barash: I think they do, but they don't live in a way that's consistent with the expectations and hopes of many people.
You write about the tiny pygmy marmoset. After the mother loses 22 per cent of her body fat during lactation, the fathers carry, feed and groom the babies. Sometimes, they even act as midwives, and some even exhibit sympathetic pregnancy: their testosterone lowers and their prolactin levels rise. Are pygmy marmosets most like the domesticated, monogamous human male?
Prof. Barash: They're pretty close. There's also the California mouse.
Dr. Lipton: Those beavers are pretty close.
Prof. Barash: Except beavers do have a divorce rate that's almost comparable to that of humans. But California mice and pygmy marmosets actually are significantly more faithful than humans.
Many of the monogamous animals have babies that require a lot of rearing. California mouse babies are cold blooded for the first two weeks, so the father has to cuddle them. Does childcare drive monogamy?
Prof. Barash: Yeah, it's pretty much needed.
Dr. Lipton: To make modern children successful, you have to invest quite a lot of energy. If you're so busy schlepping your kids to soccer lessons and orthodonture, doing the helicopter-parent thing and going to college interviews - not to mention having to pay for it - the idea of having an extra-pair copulation, the risk to your offspring may just not be worth it at that point.
Prof. Barash: That's like beavers, who have this tremendous investment in their lot and their dam.
So would aspiring monogamists do well to invest in children, a home and maybe even a business together?
Dr. Lipton: It's interesting you said that. That's kind of us. We have children we've invested a huge amount in, plus we write books together, plus we run a horse farm.
Prof. Barash: That's one of the bottom lines: if you want a good monogamous relationship, it really helps to rely upon each other.
If babies drive monogamy, why do we have a "soft spot" for people and hope to be monogamous with them even if we have no intention of having children with them?
Prof. Barash: We have an inclination [to breed]but we're also capable of manipulating these things.
Dr. Lipton: For women and men these days, babies are so expensive. You have to choose your breeding opportunities very carefully. You may have casual sex, friends with benefits or long-term lovers, and none of those copulations result in babies because you're making the choice that you're not ready to breed yet.
You say love gets us breeding, but also acknowledge that love strengthens familial bonds: Monogamous parents can free up the child because they co-operate, and aging partners help each other.
Dr. Lipton: When you get to our age and you know that in 10 or 20 years you're going to be wearing adult Depends, the benefit then of co-operation is even greater. You're going to be old and vulnerable. In some previous eras when people died really young, [monogamy]was less of a payoff.
Why do people so often pick the wrong husband or wife?
Prof. Barash: Lots of reasons. For one, decisions are often based on inadequate or misleading information: Individuals are often inclined to misrepresent their own value. What may seem attractive in the short run may be less than wonderful in the long, and as far as evolution is concerned, the short run - reproductive success - is often all that counts.
Dr. Lipton: People muddle through life, feeling horny, feeling lonely, wanting sexual partners and life partners, perhaps wanting multiple partners but also wanting fidelity for their mates. We muddle through precisely because genes whisper. They do not give explicit and reliable information about mating decisions. So what seems right one night may seem disastrous the next. Monogamous liaisons are unusual, and require saying no to basic instincts, so there is nothing compulsory about them, except as society dictates.
The key ingredients
When it comes to monogamy, the authors' inspiration comes from Prof. Barash's late parents. Married for 64 years, they were bridge partners, dance partners and business partners, selling flowers at a small shop in the New York subway.
The authors have their own tips for aspiring monogamists.
Friends with benefits The authors suggest falling in "deep like" before having sex: "Good friends make good monogamists (and better lovers, too!)"
Read the fine print Undertake an assessment of your prospective partner's genes, behaviour and resources . Assess yourself as well. "It may sound cold … but Malagasy giant jumping rats, dwarf fat-tailed lemurs, California mice … do just this, and there is no reason that human beings should settle for anything less," they write.
Know thyself "Understand that you may have penchants for being non-monogamous but that doesn't mean you're not healthy or normal or that you don't love your partner," Prof. Barash said.
Don't blame evolution "The argument that people have sex with other partners because the genes made them do it is fictitious," Dr. Lipton said. "We have judgment that can override these flavours, just like we can walk by a hot fudge sundae."